The present invention relates generally to data processing systems and more particularly to an active stream format for holding multiple media streams.
Conventional file and/or stream formats for transmitting multiple data streams of varying media are limited in several respects. First, these formats are generally limited in the packet sizes that are available for encapsulating data. Such formats, if they specify packets, specify the packets as a given fixed size. Another limitation of such formats is that they do not facilitate the use of error correction codes. A further weakness of these conventional formats is that they do not provide flexibility in timing models for rendering the data encapsulated within the format. An additional limitation with such formats is that they are not well adapted for different transport mediums that have different levels of reliability and different transmission capabilities.
In accordance with a first aspect of the present invention, a computer system has a logical structure for encapsulating multiple streams of data that are partitioned into packets for holding samples of data from the multiple data streams. A method of incorporating error correction into the logical structure is performed on the computer system. In accordance with this method, a portion of at least one packet is designated for holding error correcting data. The error correcting data is then stored in the designated portion of the packet.
In accordance with another aspect of the present invention, multiple streams of data are stored in packets and error correcting data is stored in at least some of the packets. The packets are encapsulated into a larger stream and information regarding what error correcting methods are employed for the packets is also stored in the packets.
In accordance with yet another aspect of the present invention, samples of data from multiple data streams are stored in packets, and replicas of information are stored in at least some of the packets. A flag is set in each of the packets that holds replicas to indicate that the packets hold the replicas. The packets are encapsulated into a larger logical structure and transmitted to a destination.
In accordance with a further aspect of the present invention, a logical structure is provided for encapsulating multiple streams of data where the streams of data are stored in packets. Clock licenses that dictate advancement of a clock are stored in multiple ones of the packets. The logical structure is transmitted from a source computer to a destination computer. The clock is advanced at the destination computer as dictated by the clock license for each packet that holds a clock license in response to the receipt or processing of the packet at the destination computer.
In accordance with an additional aspect of the present invention, a stream format is provided for encapsulating multiple streams of data. The stream format includes a field for specifying a packet size for holding samples of the multiple streams of data. In a logical structure that adopts the stream format, a value is stored in the field that corresponds to the desired packet size. Packets of the desired size are stored within the logical structure and the logical structure is transmitted over a transport medium to the destination.
In accordance with a further aspect of the present invention, a stream format is provided for encapsulating multiple streams of data. A field is included in a logical structure that adopts the stream format for holding a value that specifies a maximum bit rate at which the multiple streams may be rendered at the destination. A value is stored in the field and the logical structure is transmitted over a transport medium to a destination.
In accordance with another aspect of the present invention, a stream format is provided for encapsulating multiple data streams and a new media type is dynamically defined. An identifier of the media type is stored in a logical structure that adopts the stream format and packets of the new media type are stored in the logical structure.